I vaguely remember reading that there were shipping routes that would be half the time and distance if the ice was melted... And some ships run during the summer months... Mostly from Russia to Europe... Iirc...

Yes, Absolutely. A handful of years ago sailing through the North West Passage (around Alaska then across above Canada) was unheard of. Now it's quite routine, lots of people do it for fun every summer.

Probably, Russia are also building the "Polar Express" subsea cable from Murmansk to Vladivostok around Siberia so I guess is it viable now.

Also - totally unrealistic - but what if the ice freezed again, making the cables impermeable to spying and ushering in some kind of golden era of diplomacy and trust. I remember reading that in times when technology favored defense there were widespread moments of peace throughout Europe, like in the Middle Ages, so this could be something like that.